An organic electroluminescent element is a self-emitting type of light-emitting device having a pair of electrodes composed of an anode and a cathode on a substrate and an organic layer that includes a light-emitting layer in between the pair of electrodes. [These elements] are expected to find use in a variety of applications such as displays and illumination lighting.
In order for the light generated by the light-emitting layer to be extracted, at least either the anode or the cathode of the organic electroluminescent element needs to be an electrode that has optical transparency, and indium tin oxide (ITO) is generally used as an electrode having optical transparency.
Aiming at improving the light extraction efficiency of a device, an organic light-emitting diode has been proposed which comprises a transparent substrate, a light-scattering layer, a transparent first electrode layer, an organic EL element, and a transparent second electrode layer. Furthermore, it has been proposed that a low refractive-index isolation layer be provided in order to reduce the absorptivity of a reflector layer that can be disposed on the second transparent electrode layer (Patent Document 1).
With the aim of accomplishing both extraction of light at a high efficiency and improvement of electrical characteristics, an organic electroluminescent element has been proposed which has an electrode in which a first transparent conductive layer composed of conductive nanoparticles and a binder and a second transparent conductive layer composed of a conductive polymer are formed in this order on a substrate surface (Patent Document 2).